Public g As Graphics
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        g.DrawLine(Pens.Black, 10, 10, 100, 100)
        g.DrawLine(Pens.Red, 100, 10, 10, 100)
        g.Dispose()
    End Sub